An endoscope has an insertion section to be inserted into, for example, a body cavity of a subject to be examined. This insertion section is composed of a tip hard section, a bending section and a flexible section in this order from the tip end. Furthermore, an observation window, an illumination window, a forceps outlet and an air/water supply nozzle are provided on the tip end face of the tip hard section. Moreover, a camera module is mounted at the position corresponding to the observation window and a light guide is mounted at the position corresponding to the illumination window inside the tip hard section. The bending section is configured by continuously connecting a plurality of articulation ring units, whereby the tip hard section can be directed to a desired direction by wire operation. The flexible section has a length of approximately 1 to 2 min order that the tip hard section can reach a desired observation portion of a subject to be examined.
The camera module is composed of an imaging lens unit and an imaging unit. The imaging lens unit is composed of a plurality of lenses accommodated inside the housing thereof. The imaging unit has an image area sensor, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), for photoelectrically converting optical images formed by the imaging lens unit into imaging signals. The image area sensor is connected to a transmission cable via a circuit board, such as a flexible board or a sub-board. Furthermore, electronic components for driving the image area sensor are mounted on the flexible board or the sub-board. The signals from the imaging unit are transmitted to an image processing device via the flexible board or the sub-board and the transmission cable. The image processing device performs image processing for the signals and then displays, for example, the images of lesions, on a monitor.
The transmission cable for transmitting the signals from the imaging unit to the image processing device is formed of a compound multi-core cable. Since the transmission cable is inserted into the whole length of the insertion section, the transmission cable is pushed and pulled strongly each time the insertion section is looped or bent. When the transmission cable is pulled, the joint section between the transmission cable and the circuit board may be separated or the transmission cable may be disconnected in some cases.
In the endoscope described in JP-A-2013-75026, a cable connector is disposed in a space between the inner peripheral face of the tip hard section and the image area sensor to avoid problems such as the separation and disconnection described above. One end of the cable connector is fastened to the sheath of the transmission cable and the other end thereof is mounted on the mounting cylinder section of a prism holder constituting the tip hard section. Furthermore, an engaging pawl to be engaged with the tip end face of the mounting cylinder section is formed at the other end of the cable connector. Hence, even in the case that the insertion section of the endoscope is bent repeatedly and the transmission cable is pulled, the tension force is transmitted to the prism holder by the cable connector, whereby the tension force is not applied to the circuit board or the like, whereby problems such as the separation of the joint section between the transmission cable and the circuit board and the disconnection of the transmission cable do not occur.
Moreover, the electronic endoscope described in Japanese Patent No. 5436470 is also provided with a connection member for connecting the lens barrel to the signal cable and for covering at least one face of the prism. In the electronic endoscope, the end section of the cable cover of the signal cable is bonded to the inside of one end section of the connection member using an adhesive, and a pair of pawls formed at the other end section of the connection member is engaged with the rib section of the lens barrel. Hence, even if the signal cable is pulled in a direction away from the connection member, problems such as the separation of the joint section between the signal cable and the circuit board and the disconnection of the signal cable do not occur.
What's more, the endoscope described in Japanese Patent No. 5192559 is also provided with a cable mounting frame for connecting the body of the tip end section to the signal cable. In the endoscope, the engaging piece of the cable mounting frame is inserted into the engaging hole of the body of the tip end section, and the cable mounting frame is mounted rockably on the body of the tip end section, whereby the cable mounting frame is fastened to the sheath of the signal cable. Hence, even if a pushing/pulling force and a bending force are applied to the signal cable, these forces are relieved by the rocking of the cable mounting frame, whereby the durability of the endoscope is improved.